1. Field of the Invention
The present inventive subject matter relates to methods of fabricating a semiconductor device, and, more particularly, to methods of fabricating a semiconductor device in which an air-gap is formed between interconnects.
2. Description of the Related Art
With chip sizes decreasing to nanoscale, resistance-capacitance (RC) delay of interconnects within a semiconductor device and power consumption have increased.
To solve the above problems associated with interconnects of a semiconductor device, a conventional approach has been to develop low-resistance copper (Cu) interconnects and low-k dielectrics. However, this method may be limited when developing low-k dielectric having a dielectric constant (k) less than 2.5. A proposed alternative has been to form an air-gap between Cu interconnects.
According to some conventional methods, an air-gap structure may be formed using non-conformal deposition, a thermal decomposable polymer, or a di-block copolymer. However, the conventional methods may have drawbacks in that an air-gap is not easy to form at a desired region at a desired level and the shape of the air-gap cannot be easily adjusted, thereby causing defects in a semiconductor device.
Another drawback is that an air-gap generally cannot be selectively formed between interconnects, thereby degrading the mechanical strength of a semiconductor device. Still another drawback is that a separate new material may be needed to form an air-gap.